1. Field
An aspect of the present disclosure relates to a luminescent diode, a method for manufacturing the luminescent diode, and a wavelength tunable external cavity laser using the luminescent diode. More particularly, an aspect of the present disclosure relates to a superluminescent diode (SLD) operated to generate a high output by minimizing electro-optic loss, a method for manufacturing the SLD, and a wavelength tunable external cavity laser using the SLD.
2. Description of the Related Art
A superluminescent diode (SLD) is a light source having an intermediate characteristic of a light emitting diode (LED) and a laser diode (LD), and has recently come into the spotlight as a light source of an optical sensor. Such SLDs are widely used as light sources for fiber-optic gyroscopes that are used as navigation systems in vehicles, ships, airplanes, etc., optical coherence tomography that is a technique for examining, with high resolution, multiple faces of microstructures in living tissues, and wavelength division multiplexing-passive optical networks (WDM-PONs).
Meanwhile, the structure of luminescent diodes generally applied to high-output lasers operated to generate 100 mW or more includes a ridge waveguide (RWG) structure. In the RWG structure, the width of an active layer is wide, and hence a high output can be generated even at high injection current. Thus, the RWG structure is used in SLDs operated to generate a few hundreds of mW or more.
In the case of a planar buried heterostructure (PBH), the PBH has little electro-optic loss but has a narrow width of the active layer, as compared with the RWG structure. Therefore, the PBH is used for a high output, which is very limited.